The invention pertains to semiconductor processing methods, and in particular applications pertains to reactive ion etching of semiconductor substrates utilizing low concentrations of reactive etching components.
It is frequently desired during semiconductor processing to form openings in a material. Prior to, or during, the formation of the openings, a patterned mass (such as, for example, an antireflective coating), is frequently provided over the material. After the openings are etched into the material, it is frequently desired to remove the mass from over an upper surface of the material without extending a depth or width of the openings. This has proven difficult, and it would be desirable to develop improved methods for removing a mass from over an upper surface of a material.
In one aspect, the invention encompasses a semiconductor processing method in which a semiconductor substrate is exposed to reactive ion etching conditions. The reactive ion etching conditions comprise subjecting exposed surfaces of the substrate to a gas having components therein which are reactive with the exposed surfaces. A total concentration of the reactive components within the gas is less than 4.5%, by volume. In particular aspects, the total concentration of the reactive components can be less than 2% by volume, or less than 1% by volume. Exemplary reactive components are fluorine-containing components, such as NF3.
In one aspect, a semiconductor substrate includes a first mass of material, a second mass over the first mass, and an opening extending through the first mass and into the second mass. The second mass has a thickness and the opening has a width. The substrate is subjected to etching conditions which remove at least 250 angstroms from the thickness of the second mass, and which extend the width of the opening by no more than 100 angstroms, in some aspects by no more than 50 angstroms; and in some aspects by no more than 10 angstroms. In further aspects, the etching conditions extend a depth of the opening by no more than 50 angstroms, and in some aspects by no more than 10 angstroms.